A thinktank has emerged from its tank with a damp list of ideas on how to clean up the UK's urban air quality, with the key suggestion being a new scrappage scheme for the most polluting cars -- funded by an £800 one-off car tax bill for buyers of new diesels.

Richard Howard from Policy Exchange said: "Air pollution is overwhelmingly a diesel problem. Road transport is the primary source of emissions of Nitrogen Oxides (NOx) and Particulate Matter (PM) in London, and within this diesel cars and vans are the main culprits," explaining that "successive governments since the 1990s" are responsible for this thanks to encouraging the adoption of diesel cars over petrol in an effort to reduce our CO2 output.

That environmental case for supporting diesel has since collapsed, says the Exchange, quoting data from the Society of Motor Manufacturers and Traders that shows that petrol cars, weighted for sales, now output less CO2 than diesel models, and don't have anything like the same locally damaging NOx and particulate output that is the current New Bad Thing about diesel car ownership.

"We propose that HM Treasury should increase the first year VED rate for new diesels by up to £800 to reflect the greater damage done by diesels in terms of local air pollution. The £800 figure reflects the additional air pollution damage caused by a Euro 6 diesel car compared to a Euro 6 petrol car," says the report, asking for the money raised from this tax to be put into a new version of the 2009 scrappage scheme, this time focused on retiring older and more polluting diesels from the roads.